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What's the problem with short shift kits?

rossjacko

rossjacko

Car  Clio 182, V8 Landy
I've been thinking about trying to reduce the throw of the standard 182 gear lever and see it's easy enough to fit a shorter pivot arm to do so. However everywhere I read on here it's always about modified scenic shifters or PMS ones. Why are people reluctant to use a reduced length pivot arm? I'm not interested in spending a fortune on a PMS one nor particularly interested on the increased height of a scenic one, just something to reduce the throw. Thanks!
 
I always thought it was because the gearbox is crap and can't cope with the faster shifting.
 
But surely any of the kits that are installed will speed up the change time? Whether it's on the bottom of the stick or at the gearbox end, the same thing still happens...
 
Boxes dont like being rushed. The selectors and synchros are made of cheese and quick shifts wear them. The PMS shifters maintain the same throw as a standard shifter, I'd imagine a scenic one wouldn't be far away either.

Short shift kits are considerably shorter than the above but if you're careful there's really no issue with them.
 
On most cars the issue is that the excessive motion comes from wear and slop in the bushes, so when you fit a short shift, you wind up with less throw, but just as much play, which makes it feel horrible and causes you to miss gears. Always worth renewing the bushes etc before modifying the throw.

On the clio there is an additional issue that the gearbox is utter utter s**t and rushing the synchros causes them to fail fairly quickly. That said, I dont really believe that shift length is a huge contributor, if you bang it through the gears with no mechanical sympathy then an extra inch of lever travel wont save you IMHO.

The modified shifter turrets are used because the gearlever is in a stupid place, which is awkward to reach, especially with buckets and harnesses, so the PMS and megane shifter raise the ball up closer to the wheel and further back. As an aside, they also come with new bushes etc, so people tend to notice a reduction in lever travel, withough it actually being a 'short shift'

Like everything else in the car world, people take something thats 100k old and falling apart, replace it with a modified component and wax lyrical about the benefits, when most of them would have come from simply repairing or replacing what was there. Polybushes are probably the best example of this!
 
£380 to repair a crunchy 3rd and 4th gear, £250 to repair a crunchy 1st and 2nd gear. All for the sake of a £12 short shift pin.

The dog teeth on the gear and selector hub wear before the brass synchro ring - hence the prices above. This is caused by rushing the gear change and people not changing the oil in the box. Regular oil changes and decent oil helps these boxes massively.

Replacing all the bushes like what @alistairolsen has said, is the best way to remove play from the gear linkage. And it'll cost you about £4 from Renault for the main offender.
 
rossjacko said:
But surely any of the kits that are installed will speed up the change time? Whether it's on the bottom of the stick or at the gearbox end, the same thing still happens...
Click to expand...
No mate as it's a lever principle. You can alter the lengths before and after the pivot point to retain the same gear change throw. This is what Renault did with the scenic shifter. The shift pin at the box in a scenic is the same as the one found in a 172/182 for reference.
 
Davyy said:
@NorthloopCup what's your opinion on scenic/yano stiff shift? More harm than good?

and what bush is it for £4?
Click to expand...
Having used the yanoo before I'd always recommend it. Fantastic bit of kit imo. Never used a scenic shifter, so can't comment on that though.

The bush is for the shifter pin that's at the gearbox mate. I'll try and dig a part number out.
 
NorthloopCup said:
Having used the yanoo before I'd always recommend it. Fantastic bit of kit imo. Never used a scenic shifter, so can't comment on that though.

The bush is for the shifter pin that's at the gearbox mate. I'll try and dig a part number out.
Click to expand...

Thanks mate. Easy to get at when swapping a shifter over? Im going to get Rentech to do it but don't want to add too much labour!
 
Yeah I'm aware about sloppy feel with old bushes, but the physical throw is still x amount with the standard setup which feels a bit long still.

So if the throw lengths are similar to standard when moving to Scenic or PMS shifters, then they're on the most part installed only to change the position of the ball rather than the throw?

In terms of the length of the pin though. It's only the distance between the selector fork and the linkage that changes. So if that length is reduced, then there is less force going through the selector fork. So it must just be a speed issue with the short shift kits and the synchro's not agreeing with it?
 
@NorthloopCup can confirm, but if you just like the feel of a shorted shift, the presence of one on your car wont cause the box to die on its own.

Driving like a ham fisted oaf will, and a short shift allows you to do a quicker job of it.

At the end of the day, the boxes are awful, so shift slowly and match revs to give them an easier life. Whether you spend half a second pulling the stick 2 inches or 4 makes no odds, trying to change in 0.00001 does.
 
That's pretty much my thinking and half the idea of the thread. I'm mechanically sympathetic and not out to destroy the running gear. I'd happily even rebuild the gearbox if it came to it and it's possible to buy the bits on their own!
 
Davyy said:
Thanks mate. Easy to get at when swapping a shifter over? Im going to get Rentech to do it but don't want to add too much labour!
Click to expand...
Done mine recently and need to take it off again to bend it slightly. As above its a bit fiddly, wouldn't be paying someone to do it though as its only 4 bolts under the heatsheild, I did however have to undo my scorpion decat as well as there wasn't enough room to get the thing in and out.

@NorthloopCup will something like this below help a sloppy (scenic) shifter?

http://www.ebay.co.uk/itm/RENAULT-M...947064?hash=item1ea7a9e0b8:g:q9IAAOSwI~VTyUr9
 
as above, its just the exacerbation of the gearbox issues, people who want a shorter throw tend to want it to change gear faster, hence it kills boxes. but that's usually more the mindset of the user than the car itself at fault. we all know to drive them with mechanical sympathy or pay the price

I used to run a short shift, and a turbo engine on my old track car through standard Renault boxes, with no mechanical sympathy, ramming it from gear to gear. knew I was setting up for gearbox issues but its how I used to like to drive when I was younger. went through 14 gearboxes in that car over the years!oops!
 
Coops Turbo said:
as above, its just the exacerbation of the gearbox issues, people who want a shorter throw tend to want it to change gear faster, hence it kills boxes. but that's usually more the mindset of the user than the car itself at fault. we all know to drive them with mechanical sympathy or pay the price

I used to run a short shift, and a turbo engine on my old track car through standard Renault boxes, with no mechanical sympathy, ramming it from gear to gear. knew I was setting up for gearbox issues but its how I used to like to drive when I was younger. went through 14 gearboxes in that car over the years!oops!
Click to expand...
103-Ace-Ventura-When-Nature-Calls.gif
 
tbh most of them died from either diff bearings or just straight up stripping gears whilst in gear
 
So nothing to do with short shifts then?

I know a guy who did three vauxhall F20s in a weekend once by winding third gear out through the side of the case, but that's not relevant to premature synchro failure due to using a short shift kit either 😂
 
JB21 said:
Done mine recently and need to take it off again to bend it slightly. As above its a bit fiddly, wouldn't be paying someone to do it though as its only 4 bolts under the heatsheild, I did however have to undo my scorpion decat as well as there wasn't enough room to get the thing in and out.

@NorthloopCup will something like this below help a sloppy (scenic) shifter?

http://www.ebay.co.uk/itm/RENAULT-M...947064?hash=item1ea7a9e0b8:g:q9IAAOSwI~VTyUr9
Click to expand...
I couldn't say if that's the kit you need or not tbh mate as I've had no experience with the scenic shifter.

@rossjacko @alistairolsen the real issue is down to the synchro clearances/tolerances and the amount of movement in the gears themselves. I'd have to do a video of a mainshaft to show you better what I'm on about, but I just don't have the time I'm afraid! Closing these tolerances up is possible, but how deep are your pockets? Lol! You'd essentially be redesigning the gearbox..... and then you'd only end up finding the next weak point that needs attention.

I personally have never had an issue with the gear change speed on the jc5 box.

People fit scenic shifters to raise the height of the gearlever more so than to speed it up. The standard seating position and standard gear lever make for an uncomfortable driving position.
 
Thanks for the info all.

@NorthloopCup, are they poorly manufactured then? And I'm guessing there is too much play to be shimmed out?

Still comes back to the whole point of why a shorter pin makes them break - I'm still convinced that its a case of "oh ye boi I'm a racing driving now with mi short shift kit init" and people generally not giving things the mechanical sympathy they need - a shorter pin would therefore give less actual force on the fork but would increase the change speed by a couple of %, hence my need for this thread in the first place. I can't seem to think of a mechanical link between that pin and causing extra mechanical stress on the gearbox internals other than people rushing, which can happen with the standard throw anyway if you're keen enough.
 
rossjacko said:
Thanks for the info all.

@NorthloopCup, are they poorly manufactured then? And I'm guessing there is too much play to be shimmed out?

Still comes back to the whole point of why a shorter pin makes them break - I'm still convinced that its a case of "oh ye boi I'm a racing driving now with mi short shift kit init" and people generally not giving things the mechanical sympathy they need - a shorter pin would therefore give less actual force on the fork but would increase the change speed by a couple of %, hence my need for this thread in the first place. I can't seem to think of a mechanical link between that pin and causing extra mechanical stress on the gearbox internals other than people rushing, which can happen with the standard throw anyway if you're keen enough.
Click to expand...
It would mean having things remanufactured mate - there wouldn't be another way around it.

It's not the force at which the gearchange is made, it's the speed. The synchro ring has the job of slowing down/speeding the gear up when making a gear change. By adding the short shift pin, you are speeding up the job that the synchro has to do because the selector hub moves quicker. That's your mechanical link mate.
 
Yeah I didn't think it'd be a shim up job.

Yeah I understand that it's sped up as I said, but if I know that, then surely using more mechanical sympathy would help.
 
rossjacko said:
Yeah I didn't think it'd be a shim up job.

Yeah I understand that it's sped up as I said, but if I know that, then surely using more mechanical sympathy would help.
Click to expand...
Yes but the only way you'd do this would be to make a gearchange at the same speed as the original lever assembly.

Genuine question: do you know how a synchromesh works? As in the correct mechanical way?

What mechanical sympathy do you intend on using combined with a short shift pin?

I'm trying to help everyone's understanding here, not be a c**k.
 
Yeah I understand that - you're not coming across as a c**k, it's a public forum and this is useful info for everybody :)

I'm an automotive engineer by profession so am fairly well versed with these things - my mechanical sympathy with a short shift pin installed would include the likes of not thrashing it into gear quite like you can with the standard linkage for a start.
 
rossjacko said:
Yeah I understand that - you're not coming across as a c**k, it's a public forum and this is useful info for everybody :smile:

I'm an automotive engineer by profession so am fairly well versed with these things - my mechanical sympathy with a short shift pin installed would include the likes of not thrashing it into gear quite like you can with the standard linkage for a start.
Click to expand...
Unfortunately mate you're still going to rush the synchro in the same way you do with the original gear lever and no amount of mechanical sympathy can make up for the design of the gearbox.

I do understand what you're saying and the thinking behind it, but when you can rush the synchros with the oe lever, a short shift pin will only exacerbate the issue.
 
I only have one fitted because I like the way it feels... lol. I really couldn't care less about shifting quick, that's why I have a turbo to compensate for my boring driving. So what I can take away from this thread is that despite me shifting slowly it's going to eventually ruin my poor synchro's anyway? this upsets me if so.
 
cjgower said:
I only have one fitted because I like the way it feels... lol. I really couldn't care less about shifting quick, that's why I have a turbo to compensate for my boring driving. So what I can take away from this thread is that despite me shifting slowly it's going to eventually ruin my poor synchro's anyway? this upsets me if so.
Click to expand...
From what I've been told, yes.
 
cjgower said:
I only have one fitted because I like the way it feels... lol. I really couldn't care less about shifting quick, that's why I have a turbo to compensate for my boring driving. So what I can take away from this thread is that despite me shifting slowly it's going to eventually ruin my poor synchro's anyway? this upsets me if so.
Click to expand...
Well only time will tell tbh mate, but my opinion is yes. The most important thing you can do is change the oil in the box regularly - as in as often as you replace the engine oil. Using a good spec oil will also help the box to last.
 
I might look at getting it removed then to be honest. I really don't have the money to start refurbishing gearboxes and given that it makes no real difference it's better to be safe than sorry.
 
Thanks for the advice all - I'll stick with the standard setup then. May invest in a Scenic shifter as a cheaper alternative to something that won't cause damage - don't want to be spending out for a PMS if I'm honest. Potential to fab my own thing up maybe? Perhaps I'll consider a side project at work and CAD something up.
 
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